U.S. patent application number 11/425204 was filed with the patent office on 2007-05-31 for method of forming hydrophobic coating layer on surface of nozzle plate of inkjet printhead.
Invention is credited to Kae-dong Back, Jae-woo Chung, Sung-gyu KANG, Seung-mo Lim.
Application Number | 20070120889 11/425204 |
Document ID | / |
Family ID | 38086982 |
Filed Date | 2007-05-31 |
United States Patent
Application |
20070120889 |
Kind Code |
A1 |
KANG; Sung-gyu ; et
al. |
May 31, 2007 |
METHOD OF FORMING HYDROPHOBIC COATING LAYER ON SURFACE OF NOZZLE
PLATE OF INKJET PRINTHEAD
Abstract
A method of forming a hydrophobic coating layer on a surface of
a nozzle plate of an inkjet printhead includes forming a plurality
of nozzles in the nozzle plate, each of the nozzles having an exit,
stacking a film on the surface of the nozzle plate to cover the
exit of each of the nozzles, forming a predetermined metal layer on
an inner wall of each of the nozzles and an inner surface of the
film covering the exit of each of the nozzles using a plating
method, removing the film from the surface of the nozzle plate,
forming a hydrophobic coating layer on the surface of the nozzle
plate to cover the metal layer exposed through the exit of each of
the nozzles, and removing the metal layer formed on the inner wall
of each of the nozzles and the hydrophobic coating layer formed on
the surface of the metal layer.
Inventors: |
KANG; Sung-gyu; (Suwon-si,
KR) ; Back; Kae-dong; (Yongin-si, KR) ; Lim;
Seung-mo; (Suwon-si, KR) ; Chung; Jae-woo;
(Yongin-si, KR) |
Correspondence
Address: |
STANZIONE & KIM, LLP
919 18TH STREET, N.W.
SUITE 440
WASHINGTON
DC
20006
US
|
Family ID: |
38086982 |
Appl. No.: |
11/425204 |
Filed: |
June 20, 2006 |
Current U.S.
Class: |
347/45 |
Current CPC
Class: |
B41J 2/1631 20130101;
Y10T 29/49401 20150115; B41J 2/1643 20130101; B41J 2/1606 20130101;
B41J 2/1433 20130101; B41J 2/162 20130101; B41J 2/1628
20130101 |
Class at
Publication: |
347/045 |
International
Class: |
B41J 2/135 20060101
B41J002/135 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2005 |
KR |
2005-113498 |
Dec 16, 2005 |
KR |
2005-124379 |
Claims
1. A method of forming a hydrophobic coating layer on a surface of
a nozzle plate of an inkjet printhead, the method comprising:
forming a plurality of nozzles in the nozzle plate, each of the
nozzles having an exit and an inner wall; stacking a film on the
surface of the nozzle plate such that a portion of the film covers
the exit of each of the nozzles; forming a predetermined metal
layer on the inner wall of each of the nozzles and the portion of
the film covering the exit of each of the nozzles; removing the
film from the surface of the nozzle plate; forming the hydrophobic
coating layer on the surface of the nozzle plate such that the
hydrophobic coating layer covers the predetermined metal layer
exposed through the exit of each of the nozzles; and removing the
predetermined metal layer formed on the inner wall of each of the
nozzles and the hydrophobic coating layer formed on the surface of
the metal layer.
2. The method of claim 1, further comprising: forming a seed layer
on the inner wall of each of the nozzles and the inner surface of
the film covering the exit of each of the nozzles after the
stacking of the film and before forming the predetermined metal
layer.
3. The method of claim 2, further comprising: etching the
predetermined metal layer exposed through the exit of each of the
nozzles to a predetermined depth after the removing of the
film.
4. The method of claim 3, wherein the predetermined metal layer is
etched to a depth of about 1 to about 10 .mu.m.
5. The method of claim 1, wherein the predetermined metal layer is
formed using a damascening plating method.
6. The method of claim 1, wherein the hydrophobic coating layer
formed on the surface of the predetermined metal layer is removed
by a dry etching method after the predetermined metal layer formed
on the inner wall of each of the nozzles is removed.
7. A method of forming a hydrophobic coating layer on a surface of
a nozzle plate of an inkjet printhead, the method comprising:
forming a plurality of nozzles in the nozzle plate, each of the
nozzles having an exit; stacking a film on the surface of the
nozzle plate such that the film covers the exit of each of the
nozzles; forming a polymer layer on an inner wall of each of the
nozzles and an inner surface of the film covering the exit of each
of the nozzles; removing the film from the surface of the nozzle
plate; forming a hydrophobic coating layer on the surface of the
nozzle plate such that the hydrophobic coating layer covers the
polymer layer exposed through the exit of each of the nozzles; and
removing the polymer layer formed on the inner wall of each of the
nozzles and the hydrophobic coating layer formed on the surface of
the polymer layer.
8. The method of claim 7, further comprising: etching the polymer
layer exposed through the exit of each of the nozzles to a
predetermined depth after the removing of the film.
9. The method of claim 8, wherein the polymer layer is etched using
a dry etching method.
10. The method of claim 8, wherein the polymer layer is etched to a
depth of about 1 to about 10 .mu.m.
11. The method of claim 7, wherein the forming of the polymer layer
comprises: coating a polymer in a liquid state on the inner wall of
each of the nozzles and the inner surface of the film covering the
exit of each of the nozzles; and thermally treating the coated
polymer to harden the coated polymer.
12. The method of claim 11, wherein the polymer in the liquid state
is coated using a spray coating method.
13. The method of claim 7, wherein the polymer layer is formed of a
photoresist.
14. The method of claim 7, wherein the hydrophobic coating layer
formed on the surface of the polymer layer is removed through a dry
etching method after the polymer layer formed on the inner wall of
each of the nozzles is removed.
15. The method of claim 14, wherein the hydrophobic coating layer
comprises a material that is not damaged by the removing of the
polymer layer.
16. The method of claim 15, wherein the hydrophobic coating layer
comprises parylene.
17. A method of forming a hydrophobic layer on a nozzle plate of an
inkjet printhead, the nozzle plate having inner and outer surfaces
and a plurality of nozzles having nozzle openings and inner nozzle
surfaces, the method comprising: forming a first layer of a
predetermined material on the outer surface of the nozzle plate to
cover the nozzle openings; forming a second layer of a
predetermined material on the inner surface of the nozzles plate to
cover the inner nozzle surfaces and the nozzle openings; removing
the first layer to uncover the outer surface of the nozzle plate
and to expose portions of the second layer through the nozzle
openings; forming the hydrophobic layer on the outer surface of the
nozzle plate, the nozzle openings, and the exposed portions of the
second layer; and removing the second layer and the portion of the
hydrophobic layer that was formed on the exposed portions of the
second layer.
18. The method of claim 17, wherein the second layer comprises a
metal layer having at least one metal compound.
19. The method of claim 17, wherein the second layer comprises a
plurality of metal layers, each having at least one metal
compound.
20. The method of claim 17, wherein the second layer comprises a
polymer layer having at least one polymer material.
21. The method of claim 20, wherein the at least one polymer
material is a light sensitive polymer material.
22. The method of claim 17, wherein the second layer comprises a
plurality of polymer layers, each having at least one polymer
material.
23. The method of claim 17, wherein a thickness of a first portion
of the second layer formed on upper portions of the inner nozzle
surfaces is greater than a thickness of a second portion of the
second layer on remaining portions of the inner nozzle
surfaces.
24. The method of claim 17, wherein the forming of the hydrophobic
layer includes forming the hydrophobic layer on upper portions of
the inner nozzle surfaces located within a predetermined distance
from the nozzle openings.
25. The method of claim 24, further comprising: etching the second
layer to a predetermine depth before forming the hydrophobic layer
to uncover the upper portions of the inner nozzle surfaces.
26. The method of claim 17, further comprising: forming an
intermediate layer on the inner surface of the nozzle plate; and
forming the second layer on the intermediate layer.
27. The method of claim 26, wherein the intermediate layer includes
at least one metal and the second layer includes at least one
metal.
28. The method of claim 26, wherein the intermediate layer includes
a metal and the second layer also includes the metal.
29. The method of claim 26, wherein the intermediate layer
comprises a plurality of metal layers.
30. A method of forming a hydrophobic layer on a nozzle plate of an
inkjet printhead, the nozzle plate having first and second
surfaces, a plurality of nozzles having nozzle openings and inner
nozzle surfaces, and a covering layer formed on the second surface
of the nozzle plate to cover the inner nozzle surfaces and the
nozzle openings and having exposed portions exposed through the
nozzle openings to the first surface of the nozzle plate, the
method comprising: forming the hydrophobic layer on the first
surface of the nozzle plate, the nozzle openings, and the exposed
portions of the covering layer; and removing the covering layer and
portions of the hydrophobic layer formed on the exposed portions of
the covering layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C.
.sctn.119(a) from Korean Patent Applications Nos. 10-2005-0113498,
filed on Nov. 25, 2005, in the Korean Intellectual Property Office,
and 10-2005-0124379, filed on Dec. 16, 2005, in the Korean
Intellectual Property Office, the disclosures of which are
incorporated herein by reference in their entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present general inventive concept relates to an inkjet
printhead having a hydrophobic layer, and more particularly, to a
method of forming a hydrophobic coating layer on a surface of a
nozzle plate of an inkjet printhead.
[0004] 2. Description of the Related Art
[0005] An inkjet printhead is a device that ejects fine ink
droplets onto a desired position of a recording medium to print an
image of a predetermined color. The inkjet printhead may be roughly
classified into two types of printheads, depending on an ink
ejecting method employed: thermally-driven inkjet printheads and
piezoelectric inkjet printheads. A thermally-driven inkjet
printhead generates a bubble in ink using a heat source and ejects
the ink using an expansion force of the bubble. A piezoelectric
inkjet printhead deforms a piezoelectric element and ejects ink
using a pressure applied to the ink due to the deformation of the
piezoelectric element.
[0006] FIG. 1 is a sectional view illustrating a construction of a
conventional piezoelectric inkjet printhead.
[0007] Referring to FIG. 1, a channel plate 10 includes a manifold
13, a plurality of restrictors 12, and a plurality of pressure
chambers 11. A nozzle plate 20 includes a plurality of nozzles 22
corresponding to the pressure chambers 11. Also, a piezoelectric
actuator 40 is provided on an upper portion of the channel plate
10. The manifold 13 is a passage supplying ink flowing from an ink
storage (not illustrated) to each of the pressure chambers 11, and
each of the restrictors 12 is a passage through which the ink flows
from the manifold 13 into each of the pressure chambers 11. The
plurality of pressure chambers 11, which are filled with ink to be
ejected, are arranged on one side or both sides of the manifold 13.
Each pressure chamber 11 changes its volume as the piezoelectric
actuator 40 is driven, thereby creating a pressure change required
for an ejection of ink or for an in-flow of ink. A portion that
constitutes an upper wall of each of the pressure chambers 11
contained in the channel plate 10 serves as a vibration plate 14
that is deformable by a driving of the piezoelectric actuator
40.
[0008] The piezoelectric actuator 40 includes a lower electrode 41,
a piezoelectric layer 42, and an upper electrode 43 sequentially
stacked on the channel plate 10. A silicon oxide layer 31 is formed
as an insulation layer between the lower electrode 41 and the
channel plate 10. The lower electrode 41 is formed on an entire
surface of the silicon layer 31 to serve as a common electrode. The
piezoelectric layer 42 is formed on the lower electrode 41 such
that the piezoelectric layer 42 is positioned on the plurality of
pressure chambers 16. The upper electrode 43 is formed on the
piezoelectric layer 42 to serve as a drive electrode, applying a
voltage to the piezoelectric layer 42.
[0009] In the inkjet printhead having the above construction,
water-repellent processing of a surface of the nozzle plate 20 has
a direct influence on an ink ejection performance thereof, such as
a directionality and an ejection speed of an ink droplet ejected
through each of the nozzles 22. To improve an ink ejection
performance, the surface of the nozzle plate 20 outside of the
nozzles 22 should have a water-repellent characteristic, i.e.,
should be hydrophobic, and an inner wall of each of the nozzles 22
should be hydrophilic. In detail, when the surface of the nozzle
plate 20 outside of the nozzles 22 is hydrophobic, ink wetting on
the surface of the nozzle plate 20 is prevented, so that the
directionality of ejected ink may be improved. Also, when the inner
wall of each of the nozzles 22 is hydrophilic, a contact angle with
respect to an ink droplet decreases and thus capillary force
increases, so that a refill time of ink is shortened and an
ejection frequency may be increased. Also, since each of the
nozzles 22 is filled with ink up to an exit thereof, a uniformity
of ink ejection may be improved.
[0010] A method of forming a hydrophobic coating layer over the
entire nozzle plate 20 having the nozzles 22 therein using an
electron beam evaporation method has been conventionally-used.
According to this conventional method, the hydrophobic coating
layer is formed on the inner wall of each of the nozzles 22, as
well as the surface of the nozzle plate 20 outside of the nozzles
22. The hydrophobic coating layer formed on the inner wall of each
of the nozzles 22 reduces refill characteristics of ink and
ejection uniformity.
[0011] To solve these problems, conventional methods of forming a
hydrophobic coating layer only on the surface of the nozzle plate
20 are under development.
[0012] FIG. 2 is a view illustrating a conventional inkjet
printhead on which a sulphur compound layer is formed as a
hydrophobic coating layer on a surface of a nozzle plate 51
thereof.
[0013] Referring to FIG. 2, after a metal layer 52 is formed on the
surface of the nozzle plate 51 including a plurality of nozzles 55,
each nozzle 55 being formed to pass through the nozzle plate 51, a
sulphur compound is coated on the surface of the metal layer 52 to
form a sulphur compound layer 53. The sulphur compound is
selectively coated on the surface of the metal layer 52. However,
according to this method, there is a high probability that the
metal layer 52 is deposited on an inner wall of each of the nozzles
55 as well as the surface of the nozzle plate 51. Also, when a
number of the nozzles 55 is large, the metal layer 52 may be
non-uniformly deposited on different portions of each of the
nozzles 55. In this case, the sulphur compound layer 53 may be
formed on the inner wall of each of the nozzles 55 or may be
non-uniformly formed. When the sulphur compound layer 53, which is
a hydrophobic coating layer, is not properly formed, areas around
each of the nozzles 55 are easily contaminated by ink and an
ejection speed of an ink droplet is reduced or an ejection
direction of an ink droplet becomes non-uniform, so that an
ejection performance is impaired.
[0014] FIG. 3 is a view illustrating a conventional inkjet
printhead on which a water-repellent layer including a fluorine
resin is formed on a surface of a nozzle plate 70 thereof.
[0015] Referring to FIG. 3, a water-repellent layer 90 is formed on
the surface of the nozzle plate 70 having nozzles 72. This
water-repellent layer 90 includes a fluorine resin particle 94 and
a hard body 98 contained in a nickel base 96. A fluorine resin
layer 92 is formed on the surface of the water-repellent layer.
However, since nickel is reactive with a portion of ink, nickel is
undesirable for commercial use.
[0016] Japanese Patent Laid-Open Publication No. hei 7-314693
discloses a method of forming a water-repellent layer on a surface
of a nozzle plate by blowing a gas through nozzles of the nozzle
plate to prevent the water-repellent layer from being formed on an
inner surface of each of the nozzles. However, this method requires
a complicated apparatus and a difficult process, and thus it is
difficult and expensive to use this method.
SUMMARY OF THE INVENTION
[0017] The present general inventive concept provides a method of
forming a hydrophobic coating layer on a surface of a nozzle plate
of an inkjet printhead to improve ejection directionality and
ejection uniformity of the inkjet printhead and to increase an
ejection frequency.
[0018] Additional aspects and advantages of the present general
inventive concept will be set forth in part in the description
which follows and, in part, will be obvious from the description,
or may be learned by practice of the general inventive concept.
[0019] The foregoing and/or other aspects and utilities of the
present general inventive concept may be achieved by providing a
method of forming a hydrophobic coating layer on a surface of a
nozzle plate of an inkjet printhead, the method including forming a
plurality of nozzles in the nozzle plate, each of the nozzles
having an exit and an inner wall, stacking a film on the surface of
the nozzle plate such that a portion of the film covers the exit of
each of the nozzles, forming a predetermined metal layer on the
inner wall of each of the nozzles and the portion of the film
covering the exit of each of the nozzles using a plating method,
removing the film from the surface of the nozzle plate, forming the
hydrophobic coating layer on the surface of the nozzle plate such
that the hydrophobic coating layer covers the predetermined metal
layer exposed through the exit of each of the nozzles, and removing
the predetermined metal layer formed on the inner wall of each of
the nozzles and the hydrophobic coating layer formed on the surface
of the metal layer.
[0020] The method may further include forming a seed layer on the
inner wall of each of the nozzles and the inner surface of the film
covering the exit of each of the nozzles after the stacking of the
film and before forming the predetermined metal layer.
[0021] The method may further include etching the predetermined
metal layer exposed through the exit of each of the nozzles to a
predetermined depth after the removing of the film. The
predetermined metal layer may be etched to a depth of about 1 to
about 10 .mu.m.
[0022] The predetermined metal layer may be formed using a
damascening plating method.
[0023] The hydrophobic coating layer formed on the surface of the
predetermined metal layer may be removed by a dry etching method
after the predetermined metal layer formed on the inner wall of
each of the nozzles is removed.
[0024] The foregoing and/or other aspects and utilities of the
present general inventive concept may also be achieved by providing
a method of forming a hydrophobic coating layer on a surface of a
nozzle plate of an inkjet printhead, the method including forming a
plurality of nozzles in the nozzle plate, each of the nozzles
having an exit, stacking a film on the surface of the nozzle plate
such that the film covers the exit of each of the nozzles, forming
a polymer layer on an inner wall of each of the nozzles and an
inner surface of the film covering the exit of each of the nozzles,
removing the film from the surface of the nozzle plate, forming a
hydrophobic coating layer on the surface of the nozzle plate such
that the hydrophobic coating layer covers the polymer layer exposed
through the exit of each of the nozzles, and removing the polymer
layer formed on the inner wall of each of the nozzles and the
hydrophobic coating layer formed on the surface of the polymer
layer.
[0025] The method may further include etching the polymer layer
exposed through the exit of each of the nozzles to a predetermined
depth after the removing of the film. The polymer layer may be
etched using a dry etching method. The polymer layer may be etched
to a depth of about 1 to about 10 .mu.m.
[0026] The forming of the polymer layer may include coating a
polymer in a liquid state on the inner wall of each of the nozzles
and the inner surface of the film covering the exit of each of the
nozzles, and thermally treating the coated polymer to harden the
coated polymer. The polymer in the liquid state may be coated using
a spray coating method.
[0027] The polymer layer may be formed of a photoresist.
[0028] The hydrophobic coating layer formed on the surface of the
polymer layer may be removed through a dry etching method after the
polymer layer formed on the inner wall of each of the nozzles is
removed.
[0029] The hydrophobic coating layer may include a material that is
not damaged by the removing of the polymer layer. The hydrophobic
coating layer may include parylene.
[0030] The foregoing and/or other aspects and utilities of the
present general inventive concept may also be achieved by providing
a method of forming a hydrophobic layer on a nozzle plate of an
inkjet printhead, the nozzle plate having inner and outer surfaces
and a plurality of nozzles having nozzle openings and inner nozzle
surfaces, the method including forming a first layer having a
predetermined material on the outer surface of the nozzle plate to
cover the nozzle openings, forming a second layer having a
predetermined material on the inner surface of the nozzles plate to
cover the inner nozzle surfaces and the nozzle openings, removing
the first layer to uncover the outer surface of the nozzle plate
and to expose portions of the second layer through the nozzle
openings, forming the hydrophobic layer on the outer surface of the
nozzle plate, the nozzle openings, and the exposed portions of the
second layer, and removing the second layer and the portion of the
hydrophobic layer formed on the exposed portions of the second
layer.
[0031] The second layer may include a metal layer having at least
one metal compound. The second layer may include a plurality of the
metal layers, each having the at least one metal compound. The
second layer may include a polymer layer having at least one
polymer material. The at least one polymer material may be a light
sensitive polymer material. The second layer may include a
plurality of the polymer layers, each having the at least one
polymer material.
[0032] A thickness of a first portion of the second layer formed on
upper portions of the inner nozzle surfaces may be greater than a
thickness of a second portion of the second layer on remaining
portions of the inner nozzle surfaces. The forming of the
hydrophobic layer may include forming the hydrophobic layer on
upper portions of the inner nozzle surfaces located within a
predetermined distance from the nozzle openings. The method may
further include etching the second layer to a predetermine depth
before forming the hydrophobic layer to uncover the upper portions
of the inner nozzle surfaces.
[0033] The method may further include forming an intermediate layer
on the inner surface of the nozzle plate, and forming the second
layer on the intermediate layer. The intermediate layer may include
at least one metal and the second layer may include at least one
metal. The intermediate layer may include a metal and the second
layer may also include the metal. The intermediate layer may
include a plurality of metal layers.
[0034] The foregoing and/or other aspects and utilities of the
present general inventive concept may also be achieved by providing
a method of forming a hydrophobic layer on a nozzle plate of an
inkjet printhead, the nozzle plate having first and second
surfaces, a plurality of nozzles having nozzle openings and inner
nozzle surfaces, and a covering layer formed on the second surface
of the nozzle plate to cover the inner nozzle surfaces and the
nozzle openings and having exposed portions exposed through the
nozzle openings to the first surface of the nozzle plate, the
method including forming the hydrophobic layer on the first surface
of the nozzle plate, the nozzle openings, and the exposed portions
of the covering layer, and removing the covering layer and portions
of the hydrophobic layer formed on the exposed portions of the
covering layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] These and/or other aspects and advantages of the present
general inventive concept will become apparent and more readily
appreciated from the following description of the embodiments,
taken in conjunction with the accompanying drawings of which:
[0036] FIG. 1 is a sectional view illustrating a construction of a
conventional piezoelectric inkjet printhead;
[0037] FIG. 2 is a sectional view illustrating a conventional
inkjet printhead on which a sulphur compound layer is formed as a
hydrophobic coating layer on a surface of a nozzle plate
thereof;
[0038] FIG. 3 is a sectional view illustrating a conventional
inkjet printhead on which a water-repellent layer including a
fluorine resin is formed on a surface of a nozzle plate
thereof;
[0039] FIGS. 4A through 4H are views illustrating a method of
forming a hydrophobic coating layer on a surface of a nozzle plate
of an inkjet printhead, according to an embodiment of the present
general inventive concept; and
[0040] FIGS. 5A through 5G are views illustrating a method of
forming a hydrophobic coating layer on a surface of a nozzle plate
of an inkjet printhead, according to another embodiment of the
present general inventive concept.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] Reference will now be made in detail to the embodiments of
the present general inventive concept, examples of which are
illustrated in the accompanying drawings, wherein like reference
numerals refer to the like elements throughout. The embodiments are
described below in order to explain the present general inventive
concept by referring to the figures. In the drawings, thicknesses
of layers and regions may be exaggerated for clarity. A method of
forming a hydrophobic coating layer on a surface of a nozzle plate,
according to embodiments of the present general inventive concept,
may be used on a thermal-driven type inkjet printhead as well as a
piezoelectric inkjet printhead.
[0042] FIGS. 4A through 4H are views illustrating a method of
forming a hydrophobic coating layer on a surface of a nozzle plate
120 of an inkjet printhead, according to an embodiment of the
present general inventive concept. In the drawings, a partial
portion of the nozzle plate 120 is illustrated with a single nozzle
122 for convenience; however, the nozzle plate 120 includes a
plurality of nozzles 122, such as tens to hundreds of nozzles 122
arranged in a line or a plurality of lines.
[0043] First, referring to FIG. 4A, the plurality of nozzles 122,
each having a predetermined shape, are formed in the nozzle plate
120. The nozzle plate 120 may be, for example, a silicon wafer,
which is widely used to manufacture a semiconductor device.
Alternatively, the nozzle plate 120 may be, for example, a glass
substrate or a metal substrate. Each of the nozzles 122 may have a
shape such that a lower portion of each of the nozzles 122 has a
decreasing cross-section along a direction from the lower portion
to an exit of each of the nozzles 122 (i.e., a decreasing
cross-section in an exit direction), and such that an upper portion
of each of the nozzles 122 has a constant cross-section along the
exit direction. Referring to FIG. 4B, a predetermined film 130 is
stacked on the surface of the nozzle plate 120 to cover the exit of
each of the nozzles 122.
[0044] Referring to FIG. 4C, a seed layer 142 is formed on the
inner wall of each of the nozzles 122 and an inner surface of the
predetermined film 130 covering the exit of each of the nozzles
122. The seed layer 142 is a layer that allows a predetermined
metal layer 144 (see FIG. 4D) to be swiftly plated on the inner
wall of each of the nozzles 122 and the inner surface of the film
130. Here, the seed layer 142 may be formed of, for example, Cr and
Cu, in which the Cr is formed on the inner wall of each of the
nozzles 122 and the inner surface of the film 130 and the Cu is
formed on Cr. However, the seed layer 142 may be formed of various
metals besides Cr and Cu depending on a material to be plated.
[0045] Referring to FIG. 4D, the predetermined metal layer 144 is
formed on the seed layer 142 (which is formed on the inner wall of
each of the nozzles 122 and the inner surface of the film 130
covering the exit of each of the nozzles 122) using a plating
method. Here, the metal layer 144 may be formed of, for example,
Cu. However, the metal layer 144 may be formed of various metals
besides Cu. A variety of plating methods may be used to form the
metal layer 144, such as a damascening plating method. When the
damascening plating method is used to form the metal layer 144,
plating can be well performed on an upper portion of each of the
nozzles 122, which is formed narrowly at the exit of each of the
nozzles 122. Accordingly, a portion of the metal layer 144 formed
on the upper portion of each of the nozzles 122 has a thickness
that is thicker than a thickness of a portion of the metal layer
144 formed on the inner wall of each of the nozzles 122.
[0046] Referring to FIG. 4E, the film 130 stacked on the surface of
the nozzle plate 120 is removed. The film 130 may be removed, for
example, by using acetone or by manually removing the film 130 from
the surface of the nozzle plate 120. The seed layer 142 and the
metal layer 144 exposed through the exit of each of the nozzles 122
may be etched to a predetermined depth. When the seed layer 142 and
the metal layer 144 are etched to the predetermined depth, a
hydrophobic coating layer 150 (see FIG. 4F) may be formed on the
inner wall at an upper end of each of the nozzles 122, as described
below, to more effectively prevent ink wetting on the surface of
the nozzle plate 120 located on the exit of each of the nozzles
122. Here, the depth to which the seed layer 142 and the metal
layer 144 are etched may be controlled to a desired depth. For
example, the metal layer 144 may be etched to a depth of about 1 to
about 10 .mu.m.
[0047] Referring to FIG. 4F, the hydrophobic coating layer 150 is
formed on an entire surface of the nozzle plate 120 to cover the
metal layer 144 exposed through the exit of each of the nozzles
122. Referring to FIG. 4G, the seed layer 142 and the metal layer
144 formed on the inner wall of each of the nozzles 122 are removed
by, for example, using an etching process. Referring to FIG. 4H,
the hydrophobic coating layer 150 covering the exit of each of the
nozzles 122 is removed by, for example, using a dry etching
process. Alternatively, a portion of the hydrophobic coating layer
150 covering the exit of each of the nozzles 122 may be
simultaneously removed during the removing of the seed layer 142
and the metal layer 144, as opposed to being removed after the seed
layer 142 and the metal layer 144 are removed.
[0048] When the hydrophobic coating layer 150 covering the exit of
each of the nozzles 122 is removed, the hydrophobic coating layer
150 is formed on the surface of the nozzle plate 120 outside of the
nozzles 122 and on the inner wall at the upper end of each of the
nozzles 122 as illustrated in FIG. 4H. Accordingly, the surface of
the nozzle plate 120 outside of the nozzles 122 and the inner wall
at the upper end of each of the nozzles 122 are hydrophobic, and an
entire inner wall except the inner wall at the upper end of each of
the nozzles 122 is hydrophilic. According to another embodiment, an
operation of etching the seed layer 142 and the metal layer 144 to
a predetermined depth described with reference to FIG. 4E may be
omitted. In this case, the hydrophobic coating layer 150 is formed
only on the surface of the nozzle plate 120 outside the nozzles
122, and not on the inner wall at the upper end of each of the
nozzles 122.
[0049] FIGS. 5A through 5G are views illustrating a method of
forming a hydrophobic coating layer on a surface of a nozzle plate
220 of an inkjet printhead, according to another embodiment of the
present general inventive concept.
[0050] Referring to FIG. 5A, a plurality of nozzles 222 each having
a predetermined shape are formed in the nozzle plate 220. The
nozzle plate 220 may be, for example, a silicon wafer, which is
widely used to manufacture a semiconductor device. Alternatively,
the nozzle plate 220 may be, for example, a glass substrate or a
metal substrate. Each of the nozzles 222 may have a shape such that
a lower portion of each of the nozzles 222 has a decreasing
cross-section along a direction from the lower portion to an exit
of each of the nozzles 222 (i.e., a decreasing cross-section in an
exit direction), and such that an upper portion of each of the
nozzles 222 has a constant cross-section along the exit direction.
Referring to FIG. 5B, a predetermined film 230 is stacked on the
surface of the nozzle plate 220 to cover the exit of each of the
nozzles 222.
[0051] Referring to FIG. 5C, a polymer layer 240 is formed on an
inner wall of each of the nozzles 222 and an inner surface of the
film 230 covering the exit of each of the nozzles 222. Here, the
polymer layer 240 may be formed of, for example, a photoresist.
Alternatively, the polymer layer 240 may be formed of a material
other than the photoresist. The polymer layer 240 may be formed by,
for example, coating a polymer in a liquid state on the inner wall
of each of the nozzles 222 and the inner surface of the film 230
(covering the exit of each of the nozzles 222) at a predetermined
thickness, and thermally treating and hardening the coated polymer.
The polymer in a liquid state may be coated by, for example, using
a spray coating process.
[0052] Referring to FIG. 5D, the film 230 stacked on the surface of
the nozzle plate 220 is removed. Here, the film 230 may be removed,
for example, by using acetone or by manually removing the film 230
from the surface of the nozzle plate 220. The polymer layer 240
exposed through the exit of each of the nozzles 222 may be etched
to a predetermined depth. Here, the polymer layer 240 may be
etched, for example, using a dry etching process. When the polymer
layer 240 is etched to the predetermined depth, a hydrophobic
coating layer 250 (see FIG. 5G) may be formed on the inner wall at
an upper end of each of the nozzles 122, as described below, to
more effectively prevent ink wetting on the surface of the nozzle
plate 220 located on the exit of each of the nozzles 222. Here, the
depth to which the polymer layer 240 is etched may be controlled to
a desired value. For example, the polymer layer 240 may be etched
to a depth of about 1 to about 10 .mu.m.
[0053] Referring to FIG. 5E, the hydrophobic coating layer 250 is
formed at a predetermined thickness on an entire surface of the
nozzle plate 220 to cover the polymer layer 240 exposed through the
exit of each of the nozzles 222. The hydrophobic coating layer 250
may be formed of a material that is not damaged by the removing the
polymer layer 240. For example, the hydrophilic coating layer 250
may be formed of parylene.
[0054] Referring to FIG. 5F, the polymer layer 240 formed on the
inner wall of each of the nozzles 222 is removed. The polymer layer
240 may be removed by, for example, a striper, such as acetone.
Referring to FIG. 5G, when the hydrophobic coating layer 250
covering the exit of each of the nozzles 222 is removed (for
example, using the dry etching process), the hydrophobic coating
layer 250 is formed on the surface of the nozzle plate 220 outside
the nozzles 222 and the inner wall at the upper end of each of the
nozzles 222. Accordingly, the surface of the nozzle plate 220
outside the nozzles 222 and on the inner wall at the upper end of
each of the nozzles 222 are hydrophobic, and an entire inner wall
except the inner wall at the upper end of each of the nozzles 222
has is hydrophilic. According to the present embodiment, an
operation of etching the polymer layer 240 to the predetermined
depth described with reference to FIG. 5D may be omitted. In this
case, the hydrophobic coating layer 250 is formed only on the
surface of the nozzle plate 220 outside the nozzles 222, and not on
the inner wall at the upper end of each of the nozzles 222.
[0055] As described above, according to various embodiments of the
present general inventive concept, a surface of a nozzle plate
outside of the nozzles is hydrophobic, so that ink wetting on the
surface of the nozzle plate is prevented and thus directionality of
ejected ink may be secured. Also, an inner wall of each of the
nozzles is hydrophilic, so that a refill time of ink is shortened
and an ejection frequency is increased. Also, since each of the
nozzles is filled with ink up to an exit thereof, a uniformity of
ink ejection may be improved.
[0056] Although a few embodiments of the present general inventive
concept have been shown and described, it will be appreciated by
those skilled in the art that changes may be made in these
embodiments without departing from the principles and spirit of the
general inventive concept, the scope of which is defined in the
appended claims and their equivalents.
* * * * *